A problem to be coped with in such a device is how to ensure the processing of fibrous materials made from various sorts of textile fibers having different degrees of contamination. The fact that the pneumatic conditions are practically constant in the region of cleaning aperture is disadvantageous from the viewpoint of separation of impurities from materials of different types and contamination degrees and causes relatively considerable losses, due to fiber fly-off into the impurity withdrawing duct, in an effort to ensure the maximum impurity withdrawal.
According to U.S. Pat. No. 3,884,028 to Stahlecker et al for Apparatus for Removing Impurities from Fibers (the complete disclosure of which is incorporated herein by reference), it is known to provide air flow regulating means in the air supply duct which, however, is designed only for controlling or regulating the air amount flowing through said duct. This air regulating means is situated at the inlet of the air supply duct for adjusting the intensity of air flow sucked in from the ambient atmosphere. Thus, any throttling of air in this region results in an undesirable modification of air flow character in the region of the cleaning aperture and further on has unwanted effects on the air flow in the impurity withdrawing duct as well as in the air supply duct. In this way larger amounts of fibers fly off into the impurity withdrawal duct and accumulate in their transporting channels, which finally negatively influences the yarn quality.
It is an object of the present invention to eliminate the drawbacks of prior art as hereinabove referred to and to provide a device for separating impurities from variously contaminated fibrous materials made of different types of textile fibers.
Other co-assigned U.S. Patents disclosing related technology which could be helpful in understanding the present invention are: U.S. Pat. Nos. 4,429,552 (Open-end Spinning Machine); 4,495,762 (Apparatus for Separating Fibers in Open-end Spinning Units); and 4,499,718 (Apparatus for Separating Impurities from Open-end Spinning Units). The complete disclosures of these U.S. Patents is also incorporated herein by reference.